1. Field of the Invention
The present invention generally relates to fluorescent light bulbs or tubes and, more particularly, is directed to a cold-cathode fluorescent discharge tube for use in a back-light of a liquid crystal display device.
2. Description of the Related Art
The cold-cathode fluorescent discharge tube does not have a filament, so that it is advantageous when compared with a hot-cathode one in that it is small in size, high in reliability and long in life. In view of these advantages, the cold-cathode fluorescent discharge tube has been used in a back-light of a liquid crystal display for a notebook sized personal computer or the like.
In order to turn on the cold-cathode fluorescent discharge tube, a relatively high voltage is required to be applied between electrodes from an inverter so as to start the emission of radiation or discharge therebetween.
However, the conventional cold-cathode fluorescent discharge tube has such a property that it does not quickly start the discharge in response to the application of the voltage between the electrodes when it has been placed in a turned-off state for a long time, particularly, in a dark and low temperature state. Thus, it sometimes takes about one minute to place the cold-cathode fluorescent discharge tube into a stable discharge state or turn-on state after the application of the voltage. Namely, the conventional cold-cathode fluorescent discharge tube has a problem of slow start.
In order to overcome this problem, it has been suggested to increase the output voltage of the inverter. However, the increase of the voltage does not necessarily improve the start characteristic, but does enlarge an area of a wiring board mounting parts for the discharge tube because the high voltage is applied to wirings on the board. Accordingly, the size of the discharge tube becomes larger and the cost thereof becomes expensive.